3D-Printed Lithium-Ion Battery Is the Size of a Pinhead

We've discussed 3D printed robots, prosthetic noses, and even running shoes. Now a joint development effort by Harvard University, the University of Illinois at Urbana-Champaign, and visiting South Korean researchers has produced a tiny 3D printed lithium-ion battery that could be used one day as a power source for micromedical devices and robots.

This microbattery, which can fit on the head of a pin, is made by printing precisely interlaced stacks of battery electrodes -- each narrower than a human hair. The research combines two current hotbeds of research activity: 3D printing, which is poised to transform manufacturing, and lithium-ion batteries, where scientists are trying to overcome charging and degradation issues.

Harvard University, the University of Illinois at Urbana-Champaign, and visiting researchers from South Korea have demonstrated the ability to 3D print a pinhead-sized battery. These interlaced and stacked electrodes were printed layer by layer to create the working anode and cathode.(Source: Jennifer A. Lewis/Harvard University)

Shen Dillon, an assistant professor of materials science and engineering at the University of Illinois, and Jennifer A. Lewis, a professor of biologically inspired engineering at the Harvard School of Engineering and Applied Sciences, co-authored a study about their research with three Korean researchers. The National Science Foundation and the Department of Energy supported the work.

Dillon told us in an email that the research team targeted producing interdigitated filamentary electrodes with a radius comparable to the diameter of commercial oxide electrode particles. "We wanted these filaments to be relatively dense to improve the volumetric capacity and positioned closely to one another to improve transport mass kinetics -- ie, diffusion through the electrolyte," he said. "Inks are synthesized from nanoparticle powders and printed in a geometry defined by CAD software."

The main challenge the team faced was formulating the printing inks to work through a 30-micron nozzle. "The general approach is to carefully control the surface chemistry of the individual nanoparticles so that they do not stick to one another during flow under stress, but pack tightly enough together in solution that they do not flow easily in absence of an applied stress." Once the appropriate inks are produced, they can be used for a wide variety of 3D printed structures.

This tiny battery could have myriad uses in microscale systems, including energy harvesting.

"Given the theoretical limitations on battery energy density, it will never be possible that batteries this small will be able to power large devices, such as a cell phone, but there are still a number of devices that require small batteries," Dillon said. "I have always envisioned these batteries being utilized in microscale systems that both harvest and use energy. Such systems naturally require energy storage if the harvesting or use of energy is intermittent."

For example, the battery could power a micro-LED and an optical sensor that measures blood chemistry in the human body for several minutes. "Between measurements the system would have to acquire energy from the environment. This could be from a piezoelectric, thermoelectric, or wireless (RF) energy harvesting."

The battery also could be used to support "brief wireless transmissions" in single-use scenarios like tiny robots sent by the militarly on stealth missions. In these cases, there also would be a harvester present. "This could be useful in battlefield data acquisition where it may be necessary to make measurements with things like robotic insects or inconspicuous microscale devices."

1. battery power in mAh ratings is directly proportional to the physical size of the cell. 2. The future applications are going to be toward much smaller, lower power devices . The second point is validated by the fact that MEDICA Dusseldorf as identified low power design as the medical device market driver. So if the design is low power, then even a battery wil less ampere hour rating can be used.

Jim, that's a brilliant comparison. I'd still like to know exactly what process/materials they've invented and how it differs from others already in existence. The lead author, Jennifer Lewis, was quoted in an MIT Technology Review article here http://www.technologyreview.com/news/516561/a-battery-and-a-bionic-ear-a-hint-of-3-d-printings-promise/ saying that her team's method could print 2D and 3D electronics, including antennas, which sounds like the printed 3D electronic circuits Optomec is doing as we covered here http://www.designnews.com/author.asp?section_id=1392&doc_id=265097 although of course they're not made with thin-film. She also says the process is extrusion. Another similarity with Optomec is that in this same MIT article, Lewis talks about the potential for integrated electronics.

Ann-You know what the article's image reminded me of, were MEMS devices, etched from silicon. The 3D printing might be just the disruptive technology that the MEMS industry needed, as the silicone-etching process is so cost prohibitive.

Remember that battery power in mAh ratings is directly proportional to the physical size of the cell. While this is a breakthrough for 3D printing, there is a long way to go before it could power a pace-maker – if ever. I think the future applications are going to be toward much smaller, lower power devices.

Charles - your 800 uM estimate seems about right, from the scale in the image. It looks like 800 or maybe 1,000.

But I have a difficult time envisioning uM's, or microns. In order to wrap my head around that tiny number I had to convert it to a unit I am much more familiar with, being either millimeters or thousands of an inch, which I understand better in my head.

vimalkumarp --My thoughts exactly. I know the technology is somewhat distant but when ready, I can see a device such as this powering a pace maker or maybe a pump implant delivering medication to a diabetic. This is the type of life-saving R&D worth the time and money. Also, the probability of powering sensors needing somewhat low power would seem to be a suitable candidate for this 3D device. Great post Elizabeth. Very informative.

Lonegity is also another important criteria in the batteries used for implantable medical devices. There is an increase in number and types of implanatable devices and power ratings of these are different understandably. Like rating for a cochlear implant battery may be different for ICD requirement and same is true with longevity.

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